1. Field of the Invention
The present invention relates generally to a fuel interrupt arrangement for an automotive fuel tank. Particularly, the present invention relates to a fuel interrupt/pressure release valve arrangement for a fuel tank which can prevent overflow, or spillage of fuel to the outside of a fuel tank when a vehicle operates or parks on inclines, hill, steep angles etc., or when a vehicle is in a roll-over condition.
2. Description of the Prior Art
A fuel interrupt arrangement is well known which is provided for preventing spillage of fuel when a vehicle operates on inclines, or turns etc. In such a fuel interrupt arrangement, a float is provided for blocking an outlet from a fuel tank, which outlet is normally connected to an evaporation tube and a canister. In such arrangement, when a vehicle turns or operates on a hill, etc., the float is buoyed upward. An upper surface of the float is provided with means for blocking the fuel tank outlet thus preventing spillage of fuel.
However, in such arrangements, if a pressure within a fuel tank is substantially high, separation between the upper surface of the float and the outlet may be prevented, causing the valve to become stuck. To prevent this, the float must be made substantially large and heavy, increasing vehicle weight and taking up space in the fuel tank.
To prevent sticking, a fuel interrupt arrangement for preventing spillage of fuel outside of a vehicle fuel tank has been disclosed in Japanese Utility Model First Publication (unexamined) No. 62-75278. In the above mentioned application, a casing of the fuel interrupt arrangement is provided with a release valve thereon. Thus according to this structure, when the float closes the outlet and pressure within the fuel tank is substantially high, the release valve opens to release pressure within the tank to prevent sticking of the valve. In this arrangement, a valve opening pressure must be selected below a pressure at which sticking occurs (hereinbelow, sticking pressure), according to this, if a release pressure is to be set substantially low, the sticking pressure must be lowered accordingly, requiring a larger float. Accordingly, there no practical way to increase the sticking pressure beyond a certain level.
Therefore, it has been required to provide a release valve which can resist sticking thereof and in which a sticking pressure can be suitably set and which is substantially small in size and low in cost.